Reclaiming tin-scrap.



rirurnn srnrnsrarnnr OFFICE.

ELMER A. SPERRY, OF BROOKLYN, NEW YORK.

REGLAIMING TIN-SCRAP.

amount of twenty dollars'per ton, yet the mass as it stands brings onlya very small fraction of this sum, as there are but few'uses to which itcan be put, 'one of thembeing to melt and cast into rough forms such aswindow Weights, flask weights, etc., where hardhead may be employed.Iron in this form is practically worthless, as it is almost impossibleto machine it or work it in any manner. It is therefore the r'e-claimingof'these values which constitutes the object of the present invention.

The conditions in the case'of tin scrap, are

peculiar, for while the'iron with a-small traceof tin isfpraotically-Worthless, the same in a measure is true of the tin after being removed.from the scrap, especially while it contains a small percentage of iron.To illustrate, the great use of tin is in the production of tin plate.For this purpose pure tin is required as impurities dull the luster andrender the plate lessresistive and more easy of attack by oxygen,moisture, etc. For this pur ose the tinshould be at least .995 fine. tis well-known that tin has the peculiarity of alloying with nearly "allother metals. Were tin merely on the surface of the iron or steel plate,its removal might be easily accomplished, but its usefulness would inall probability bevery limited. As it is there is no clearly definedsurface-line or junction, but on the contrary there exists a layer orzone where the two metals are actually alloyed or dissolved in eachother, which assures a re- 1 markable degree of adhesion and persistenceto the tin coat. The tin might be removed down to this zone of alloy butthis, has been found to leave a prohibitive amount of tin on the blackscrapf which should not carry to exceed four-hundredths per cent. tin tobe commercial. In fact de'nuding tin scrap of its tin'down to the pointrequired becomes a difiicult problem'and involves removing at leastsixty-four sixty-fifthsor thereabouts of Specification of LettersPatent. Application filed October 8.1906. Serial No. 337.883.

IPatented Feb. 18, 1908.

the total tin. Another problem is also involved, namely that of savingthe tin thus removed in a condition from which its values may berecovered, for as we have seen it must be pure and no processes are nowreclamation of tin scrap, I mean the substantial reclaiming of fullvalues of each of the elements; this, to my knowledge, has never beenaccomplished in the manner set forth herein.

' In the case of both acid-and alkaline solvents, the black scrap ispractically ruined, or the subsequent neutralizing and bringing intocommercial condition is so expensive as to'be prohibitory. Furthermorethe tin so removed is usually-contaminated with iron to a degree whichmakes substantial inroads on the tin values recovered.

Electrolysis, especially in alkaline solution aids in preserving theblack scrap from de structive oxidation, but if pushed to a commercialpoint of removal of tin, the tin sponge or product produced runs high iniron. 4

i Processes have been su gestedwhere the scrap is treated direct in soutions and also in anhydrous liquids, but nothingcommercial in this linehas yet been roduced. In this connection it is onlyun er peculiarconditions that commercial resultscan ever be expected to follow in theapplication or development of a li uid worth say five dollars per allon,especia y where the liquid is more or Iess volatile and where thesurfaces involved are over a quarter of an acreper ton of scrapsubjected to the process. In this case a com aratively slight loss ofthe material wou d be disastrous and it isalso only under peculiarconditions that all of the surfaces, especially where more or lesscompacted into extensive capillary crevices even if reached, can becleared of the material. Again, most of these materials are corrosive inthe extreme, and if allowed to remain even 1n greatly diluted form uponthe surface, destructive corrosion is found to begin forthwith, notstopping until all of the b ack scrap stroyed.

of tin reclaimed and put into commercial form, but also selecting a formfor the tin, such as a tin compound which has avalue con-' siderably inexcess of regulin metal. To illustrate thesefsteps, I may say that oneform of concentration may consist in electrolyzing the scrap in analkaline solution wherein the solution is so constituted that such ironas is necessarily dissolved, especially from the alloyed zone abovedescribed, during the complete removal of the tin is deposit-' ed in aform'where it may be subseg uently' removed. As an illustration of thiseature I would say that an alkalmeelectrolyte, say

. sodium hydrate associated with more or less of a halogen salt willdeposit the iron factor,

either in the form of ferro-ferricoxidor as metallic iron, commingledwith the tin sp on e. The spon e is then taken, preferably un er seal orVVlfilOllt exposureto the air,.and treated for arresting, first itsoxidation by the air, and secondly, its conversion into stannate. Thislatter feature is of special advantage inasmuch as a very small residualsodium fac tor of the electrolyte serves to combine with a very largequantity of tin. I prefer to leave the tin in so far as possible in itsmetallic state instead of being combined with oxygen or any otherelement. I thenfurther concentrate the tin sponge. To illustrate thisstep,

I may run it through one or more magnetic separators, with or withoutpulverization the ironfactor may thus be almost wholly removed. It isnow in suitable sha e to be simply melted, preferably under sea andreclaimed in the form of highly refined tin, practically free from iron;or I may proceed further and" utilize the fact that the tin is alreadyin a highly comminuted state and proceed to convert this tin into someof its chemical forms, choosing those especially suited to the physicalcondition of the product. To illustrate this step, Iwould 3 say that theproduct is thoroughly dried and brought into contact with the reacting aent, for instance, chlorin. prefer to submerge the product in a liquor,preferably an anhydrous liquor, for instance, tetra chlorid of tinwithin a suitable reaction vessel provided with means for agitation andalso means for temperature control, and under these conditions introducethe chlorin in such a manner that it may be first absorbed The blackscrap I render alkaline To accomplish t us I the liquor and then passedon to the tin,

which between given tem erature limits, say. 4

l5and 1'00 centigrade', wil be found to react, forming stannic chlorid.The gases as they are introduced, and alsothe effluent gases from such abody or reacting mass, must be heated, or say insulated or covered, sothe heat which they contain, which should be above 65 de rees centirade, should not .esca e; the c orin toget er with any comming ed gasesshould be dry before being introduced. The effluent ases I treat invarious. ways,

first, I may 0 ,'ll them, thereby producing a twofold result; firstcondensing the fuming chlorid, and, secondly, depositing the stannichydrid in the form of crystals, causing in this way a separation ofthese two products.

The residuary gases are then treated with-solvents, referably at atemperature above the escape at the bottomfor the li uids and any sortof large opening to provide ee access for the removal of the crystals.From this condenser the residuary gases and vapors may be led through ascrubber or tower where they may be exposed to a very greatly extendedsurface of,- or surface wetted by, a

suitable solvent, such, for instance, as a weak solution of stannouschlorid, which it will be seen will at once dissolve both the stannicchlorid vapors and the chlorin.-

The processes outlined above may go forward until the re-action vesselhas become sufficiently filled with the accumulated anhydrous stannicchlorid, it is purified as by distillation and to this end the cooling jackets may now be employed, or other heating means may be utilized forpurposes of boiling and'distilling off, preferably while still in astate of agitation. This step consists in driving off the chlorin whichit is first desirable to remove before proceeding with the distillationproper. To remove the chlorin I prefer to introduce a calculated amountof additional tin powder, but I may drive it off by heating the liquorand allowing the effluent vapors from thecondenser to pass to thescrubber as explained.

Vapors of anhydrous tetrachlorid of tin being suitably condensed, theproduct may be accumulated in iron drums which may be utilized forshipment of the material direct. The process of distillation proceedsuntil onlya small residue exists,'which is gradually dried to a pointWhere no further distillation is produced. The condenser is then out outand air, preferably heated air, is introduced while still agitating theresidue, the fumes being led to the scrubber as explained,

this 0 eration going forward until the residues ave been thoroughlydriedand the stannic chlorid removed therefrom. In the latter part ofthis process dust tends to rise and interfere with its operation. Theresi-' dues of this process are found to consist in such slight amountsof tin powderas have become oxidized, together with any iron, lead orother metals or non-metallic elements that may have been introduced withthe powder. The values from these are recovered bycsuitableconcentration, first, separation,preferably' a magnetic separation,-ofthe dry residue and smelting-"the concentrate, either direct or afterneutralization and precipitation, and leaving in an alkaline reaction asby an alkaline solution, such, for instance, as NaOH or milk of lime.The tin product thus procured is a material consisting of 45.7 of tinand 54.3 per cent. of chlorin in the form of a water whitedistillate,perfectly chemically pure, and constitutes when greatly diluted withpure water the purest and most effective mater1al known for mordanting,weighting and otherwise treating fibers and fabrics, and commands aprice, as it should, which isin excess of the sum of. the prices of theingredients.

While I have described one method of carrying my process of reclaimingtin scrap into effect, yet I do not wish to be limited in exact detailof the steps themselves or their relation one to 'the other, as theforegoing description is simply given as illustrating one method ofcarrying the process into effect. It will'therefore be seen that stepsmay be substituted for some of those described whereby the ends that areto be gained may be accomplished, and others may be omitted withoutinterfering with the successful prosecution of the process, and theinvention ex.- tends to such use. v

By following the above specification it will be seen that we havereclaimed to the very fullest degree the values of the tin scrap, havingproduced from the iron the highest grade of wrought material and in formparticularly suited for furnacing, and from the tin factor there hasbeen produced a tin compound which is of value considerably in excess ofthe sum of the values of its ingredients. It will furthermorebe seenthat the step of first concentrating the tin scrap before proceedingwith the reclamation of its values affords great advantage over theprocesses which have heretofore been proposed inasmuch as when it isdesired to utilize the tin valuesto anything like their fullest extent,we are not confronted with the problem of treating enor mous masses withexpensive liquids or evolving on these enormous surfacessuch expensiveliquids, but in the other hand have simply to treat a very small tinconcentrate,

the bulk and about one-fortieth of the weight, and it thus comes aboutthat this treatment becomes thoroughlypractical and commercial,involving as it does only very small quantities of any liquid re-agentor carrier, and also an extremely small reaction vessel. Again the stepsof farther concentrating and refining the tm concentrate has theadvantage that the mass treated is highly concenrepresenti'ng only aboutone-hundredth of i trated and only a very slight quantity of residueremains which may carry off the values and require reclaiming andre-treatment to prevent losses.

The substance produced in the above case, viz: tetra chlorid of tin isoneof peculiarinterest and significanceinasmuch as it ma be distilledand therefore rendered perfectly chemically pure, while at the same timeit affords the basis of producing nearly all the other useful tincompounds, namely, stannous chlorid, tin. oxid, and regulin metal, allof which bodies are of almost perfect constitu tion and of extremepurity.

I claim:

1. The method of reclaiming tin scrap which consists in concentratingthe tin values, removing the black scrap, treating the im pure tinconcentrate with free chlorin in the presence of anhydrous stannicchlorid, removing the excess chlorin from the chlorid and distilling offthe stannic chlorid from the residues.

2. The method of reclaiming tin scrap merging the tin concentrate in ananhydrous liquid and treating the same-with chlorin.

' 4. The method of reclaiming tin scrap which consists in concentratingthe material by electrolysis in an alkaline bath, removing the blackscrap treating the tin concentrate to render it comparatively inert withregard tothe air, I v

5. The method of reclaiming tin scrap which consists in concentratingthe material by electrolysis in an alkaline bath, removing the blackscrap treating the tin concentrate to render itcomparatively inert asagainst farther chemical action onthe part of the electrolyte.

6. The method ofreclaiming tin scrap which consists in concentrating thematerial by electrolysis in an alkaline bath, removing the black scraptreating the tin concentrate to neutralizesame.

' 7. The method of reclaiming tin scrap which consists inelectrolytically concentratmg the material, in an electrolyte which isactive with reference to the tin concentrate,

washing the concentrate removing the black scrap and then treating itchemically to arrest tlfie action of the electrolyte in the presenceair.

8. The method of reclaiming tin scrap which consists in concentratingthe tin factor, removing the black-scrap therefrom, drying the tinconcentrate and converting the tin concentrate into an anhydrouscompound for the purpose specified.

9. The method of retaining tin scrap which consists in concentrating thetin factor, removing the black scrap therefrom, treating the tinconcentrate'to further concentrate same and then converting the tinc'oncene trate into an anhydrous compound for the purpose specified.

10. The method of reclaiming tin scrap -which consists in concentratingthe tin factor, removing the black scrap therefrom, submerging the tinconcentrate in an anhydrous liquid, agitating the mass, and treatingsuch agitated mass with chlorin.

11. The method of reclaiming tin scrap which consists in concentratingthe tin factor, removing the black scrap therefrom,v

' submerging the tin concentrate in a mass of anhydrous stannic chlorid,and treating. the

mass with chlorin.

J 12. The method ofreclaiming tin scrap which consists in concentratingthe tin factor, removing the black scrap therefrom, submerging' the tinconcentrate in a mass of anhydrous stannic chlorid, agitating the mass,and treating the same with chlorin.

13. The method of reclaiming tin scrap which consists in concentratingthe tin factor, removing the tin scrap. therefrom, submerging the tinconcentrate in a mass of anhydrous stannic chlorid, treating the massdistilling stannic which consists in concentrating the tin factor,vremoving the black scrap therefrom, submerging the tin concentrate in amass of anhydrous stannic chlorid, treating same with chlorin, treatingthe mass with tin for absorbing the excess'chlorin and then distillingthe stannic chlorid from such mass.

17. The method of reclaiming tin scrap which consists in concentratingthe tin factor, removing the black scrap therefrom, subnfrging the tinconcentrate in'a mass of anhydrous stannic' 'chlorid, treating the masswith chlorin, and then distilling stannic chlorid from the mass underconditions of agitation.

. 18. The method of reclaiming tin scrap which consists in concentratingthe tin factor, removing the black scrap therefrom, submerging the tinconcentrate in a mass of anhydrous stannic chlorid, treating the masswith chlorin, distilling stannic chlorid from the mass with heat to apre-determined point and then with the addition of aminert 19. Themethod of reclaiming tin scrap which consists in concentrating the tinfactor, removing the black scrap therefrom, submerging the tinconcentrate in a mass of anhydrous stannic chlorid, treating the masswith chlorin, distilling stannic chlorid from the mass withheat to apredetermined point. and then with the addition of a heated inert gas.

20. The method of reclaiming tin scrap which consists in concentratingthe tin factor, .removing the black scrap therefrom, submerging the tinconcentrate in a mass of anhydrous stannic chlorid, treating the masswith chlorin, distilling stannic chlorid from the mass with heat to a.re-determined point and'then with the addltion of heated air.

21. The method of reclaiming tin scrap which consists in concentratingthe tin factor, removing the black scrap therefrom,

submerging the tin concentrate in a mass .ofv

anhydrous stannic chlorid, treating the mass with chlorin, distillingstannic chlorid from the mass with heat to a pre-determined .point andthen with the addition of an inert gas under conditions'of agitation.

22. The method of reclaiming tin scrap which consists in concentratingthe tin factor, removin the black scrap therefrom, submerging tide tin,concentrate in a mass of anhydrous stannic chlorid, treating the masswith chlorin, and then distilling stannic chlorid from the mass,removing the residues and smelting saine.

23. The method of reclaiming tin scrap which consists in concentrating,submrging the tin concentrate in a mass of anhydrous stannic chorlid,treating the mass with chl'orin, and then distilling stannic chlorid,from the mass, removing the residues, concentrating and. smelting same.

24. The method of reclaiming tin scrap which consists in concentratingthe tin factor, removing the black scrap therefrom,

submerging the tin concentrate in amass of anhydrous stannic chlorid,treating the mass with chlorin, and then distilling stannic chlorid fromthe mass, precipitating the residues as described and concentrating theprecipitate.

25. The method of reclaiming tin scrap which consists inelectrolytically concentrating the tin values in an electrolytecontain-v ing the tin factor in an alkaline electrolyte,

removing the resulting black scrap, washing and rinsing same, treatingsuch scrap with an alkaline solution and while in an alkaline reactionbilleting same; removing the tin concentrate, washing and drying same toprevent oxidation, drying and heating same and treating'the concentratewith chlorin in the presence of a suitable anhydrous liquid, underconditions of agitation. and' temperature control, treating theresulting chlorid for the removal of excess chlorin,

separating same from theresidues and treating the residues substantiallyas described.

In testimony whereof I have hereunto set my hand in presence-oftwo'subscribing witnesses.

ELMER A. SPERRY.

Witnesses:-

EI HN MALONE, E. F. HUDsoN.

